Facial emotion recognition of sadness relates to superior parietal gray matter volume in mild cognitive impairment

Mild cognitive impairment (MCI) is associated with early, regionally selective neurodegenerative changes that may affect socioemotional functioning before atrophy becomes widespread. This study examined whether structural brain alterations in MCI relate to facial emotion recognition performance. Sixty adults (30 MCI, 30 healthy controls), aged 50-86 years, completed neuropsychological testing, the Facial emotion composite Task, and structural MRI. Whole-brain voxel-based morphometry revealed no significant gray matter volume differences between groups. However, targeted region-of-interest ROI analyses demonstrated lower right amygdala and bilateral hippocampal volumes in patients with MCI. Cortical thickness analyses identified two regions with lower thickness in MCI: the right superior parietal lobule and the left posterior insula. A significant Group × Sadness interaction indicated that the association between left superior parietal gray matter volume and sadness recognition differed between groups. Follow-up analyses of the extracted values showed a positive association in MCI, although this within-group association did not reach statistical significance, and a significant inverse association in HCs. These findings suggest that early MCI involves selective thinning in association cortices supporting attention and salience processing. The sadness-specific interaction indicates that patients with MCI may rely on preserved superior parietal structure during sadness recognition, a pattern that is consistent with structural reserve accounts, although this interpretation remains speculative given the cross-sectional design.